1. Field of the Invention
The present invention relates in general to internal combustion engines and more particularly to the internal combustion engines of a direct fuel injection type in which fuel is directly injected into a cavity of the piston in each cylinder to produce an air/fuel mixture and the mixture is ignited by an ignition plug.
2. Description of the Related Art
One of the internal combustion engines of the above-mentioned direct fuel injection type is shown in Laid-open Japanese Patent Application (Tokkaihei) 11-82028, that enables a so-called stratified combustion.
In the engine disclosed in the publication, each piston has a reentrant type cavity, and a fuel injection valve is arranged just above the cavity so that fuel is injected toward the cavity. That is, atomized fuel injected from the injection valve is forced to collide obliquely against a peripheral wall surface of the cavity to produce a circulation of the atomized fuel that is directed toward a center of the cavity thereby to produce an appropriate stratified air-fuel mixture over the cavity. Ignition of the mixture is effected by an ignition plug that is located beside the fuel injection valve.